水泥基超高性能混凝土增强增韧试验研究

Experimental Research on Strengthening and Toughening of Cement-based Ultra-High Performance Concrete

水泥基超高性能混凝土是由水泥、级配良好的石英砂、高效减水剂、外掺剂及硅灰、粉煤灰、钢纤维等材料组成的新型水硬性胶凝复合材料。在优化UHPC配合比的基础上,试验研究了胶凝材料、骨料级配和钢纤维掺量等因素对UHPC抗压强度和韧性的影响,同时对比分析了3种不同养护方式下其抗压强度的差异,由试验结果可知:250℃的高温养护可以显著提高混凝土的抗压强度,总平均值为163.5 MPa,较标准养护下的抗压强度提高27%,较热水养护条件下的抗压强度提高10.8%;硅灰的掺量比例为胶凝材料的15%左右时,对UHPC抗压强度的提升效果最好;在石英砂级配中,粗砂、中砂、细砂的最佳比例为1∶4∶3,可以得到较好的骨料密实度,提高UHPC的抗压强度;钢纤维的体积掺量为2.5%左右对UHPC的抗压强度和韧性提升效率较高。

The cement-based ultra-high performance concrete is a new type of hydraulic cementitious composite composed of cement,well graded quartz sand,superplasticizer,admixture,silica fume,fly ash,steel fiber and other materials.On the basis of optimizing the mix proportion of UHPC,the effects of cementitious materials,aggregate gradation and steel fiber content on the compressive strength and toughness of UHPC were studied.At the same time,the differences of the compressive strength under three different curing methods were compared and analyzed.The experimental results show that high temperature curing at 250℃can significantly increase the compressive strength of concrete.The total average value is 163.5 MPa,which is 27%higher than the compressive strength under standard curing and 10.8%higher than the compressive strength under hot water curing conditions.when the proportion of silica fume is about 15%of the cementitious material,the improvement effect of UHPC compressive strength is the best.In the quartz sand grading,the best proportion of coarse sand,medium sand and fine sand is 1:4:3,which can get better aggregate density and improve the compressive strength of UHPC.When the volume proportion of steel fiber is about 2.5%,the improvement efficiency of UHPC compressive strength and toughness is higher.